From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751053AbdE2Skx (ORCPT ); Mon, 29 May 2017 14:40:53 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:34936 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750921AbdE2Skw (ORCPT ); Mon, 29 May 2017 14:40:52 -0400 Date: Mon, 29 May 2017 20:40:49 +0200 From: Boris Brezillon To: Masahiro Yamada Cc: linux-mtd@lists.infradead.org, Marek Vasut , Richard Weinberger , linux-kernel@vger.kernel.org, Cyrille Pitchen , Brian Norris , David Woodhouse Subject: Re: [PATCH] mtd: nand: check ecc->total sanity in nand_scan_tail Message-ID: <20170529204049.25cb8c30@bbrezillon> In-Reply-To: <1495687820-30692-1-git-send-email-yamada.masahiro@socionext.com> References: <1495687820-30692-1-git-send-email-yamada.masahiro@socionext.com> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 May 2017 13:50:20 +0900 Masahiro Yamada wrote: > Drivers are supposed to set correct ecc->{size,strength,bytes} before > calling nand_scan_tail(), but it does not complain about ecc->total > bigger than oobsize. > > In this case, chip->scan_bbt() crashes due to memory corruption, but > it is hard to debug. It would be kind to fail it earlier with a clear > message. > > Signed-off-by: Masahiro Yamada Applied to nand/next. Thanks, Boris > --- > > I was actually hit by this case. > > I wasted half a day until I figured out my coding mistake in my > Denali driver. It will be helpful to check this in NAND core. > > > drivers/mtd/nand/nand_base.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c > index f4d686192717..14d6a5aa3ee8 100644 > --- a/drivers/mtd/nand/nand_base.c > +++ b/drivers/mtd/nand/nand_base.c > @@ -4970,6 +4970,11 @@ int nand_scan_tail(struct mtd_info *mtd) > goto err_free; > } > ecc->total = ecc->steps * ecc->bytes; > + if (ecc->total > mtd->oobsize) { > + WARN(1, "Total number of ECC bytes exceeded oobsize\n"); > + ret = -EINVAL; > + goto err_free; > + } > > /* > * The number of bytes available for a client to place data into